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+//
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+// Condition.h
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+//
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+// $Id: //poco/Main/Foundation/include/Poco/Condition.h#1 $
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+//
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+// Library: Foundation
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+// Package: Threading
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+// Module: Condition
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+//
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+// Definition of the Condition class template.
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+//
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+// Copyright (c) 2007, Applied Informatics Software Engineering GmbH.
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+// and Contributors.
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+//
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+// Permission is hereby granted, free of charge, to any person or organization
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+// obtaining a copy of the software and accompanying documentation covered by
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+// this license (the "Software") to use, reproduce, display, distribute,
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+// execute, and transmit the Software, and to prepare derivative works of the
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+// Software, and to permit third-parties to whom the Software is furnished to
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+// do so, all subject to the following:
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+//
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+// The copyright notices in the Software and this entire statement, including
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+// the above license grant, this restriction and the following disclaimer,
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+// must be included in all copies of the Software, in whole or in part, and
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+// all derivative works of the Software, unless such copies or derivative
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+// works are solely in the form of machine-executable object code generated by
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+// a source language processor.
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+//
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+// THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
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+// IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
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+// FITNESS FOR A PARTICULAR PURPOSE, TITLE AND NON-INFRINGEMENT. IN NO EVENT
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+// SHALL THE COPYRIGHT HOLDERS OR ANYONE DISTRIBUTING THE SOFTWARE BE LIABLE
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+// FOR ANY DAMAGES OR OTHER LIABILITY, WHETHER IN CONTRACT, TORT OR OTHERWISE,
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+// ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER
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+// DEALINGS IN THE SOFTWARE.
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+//
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+
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+
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+#ifndef Foundation_Condition_INCLUDED
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+#define Foundation_Condition_INCLUDED
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+
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+
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+#include "Poco/Foundation.h"
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+#include "Poco/Mutex.h"
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+#include "Poco/ScopedUnlock.h"
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+#include "Poco/Event.h"
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+#include "Poco/Exception.h"
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+#include <deque>
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+
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+
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+namespace Poco {
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+
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+
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+class Foundation_API Condition
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+ /// A Condition is a synchronization object used to block a thread
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+ /// until a particular condition is met.
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+ /// A Condition object is always used in conjunction with
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+ /// a Mutex (or FastMutex) object.
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+ ///
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+ /// Condition objects are similar to POSIX condition variables, which the
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+ /// difference that Condition is not subject to spurious wakeups.
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+ ///
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+ /// Threads waiting on a Condition are resumed in FIFO order.
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+{
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+public:
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+ Condition();
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+ /// Creates the Condition.
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+
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+ ~Condition();
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+ /// Destroys the Condition.
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+
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+ template <class Mtx>
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+ void wait(Mtx& mutex)
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+ /// Unlocks the mutex (which must be locked upon calling
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+ /// wait()) and waits until the Condition is signalled.
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+ ///
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+ /// The given mutex will be locked again upon
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+ /// leaving the function, even in case of an exception.
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+ {
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+ ScopedUnlock<Mtx> unlock(mutex, false);
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+ Event event;
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+ {
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+ FastMutex::ScopedLock lock(_mutex);
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+ mutex.unlock();
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+ enqueue(event);
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+ }
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+ event.wait();
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+ }
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+
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+ template <class Mtx>
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+ void wait(Mtx& mutex, long milliseconds)
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+ /// Unlocks the mutex (which must be locked upon calling
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+ /// wait()) and waits for the given time until the Condition is signalled.
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+ ///
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+ /// The given mutex will be locked again upon successfully leaving the
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+ /// function, even in case of an exception.
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+ ///
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+ /// Throws a TimeoutException if the Condition is not signalled
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+ /// within the given time interval.
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+ {
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+ if (!tryWait(mutex, milliseconds))
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+ throw TimeoutException();
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+ }
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+
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+ template <class Mtx>
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+ bool tryWait(Mtx& mutex, long milliseconds)
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+ /// Unlocks the mutex (which must be locked upon calling
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+ /// tryWait()) and waits for the given time until the Condition is signalled.
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+ ///
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+ /// The given mutex will be locked again upon leaving the
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+ /// function, even in case of an exception.
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+ ///
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+ /// Returns true if the Condition has been signalled
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+ /// within the given time interval, otherwise false.
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+ {
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+ ScopedUnlock<Mtx> unlock(mutex, false);
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+ Event event;
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+ {
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+ FastMutex::ScopedLock lock(_mutex);
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+ mutex.unlock();
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+ enqueue(event);
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+ }
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+ if (!event.tryWait(milliseconds))
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+ {
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+ FastMutex::ScopedLock lock(_mutex);
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+ dequeue(event);
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+ return false;
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+ }
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+ return true;
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+ }
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+
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+ void signal();
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+ /// Signals the Condition and allows one waiting thread
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+ /// to continue execution.
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+
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+ void broadcast();
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+ /// Signals the Condition and allows all waiting
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+ /// threads to continue their execution.
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+
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+protected:
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+ void enqueue(Event& event);
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+ void dequeue();
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+ void dequeue(Event& event);
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+
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+private:
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+ Condition(const Condition&);
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+ Condition& operator = (const Condition&);
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+
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+ typedef std::deque<Event*> WaitQueue;
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+
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+ FastMutex _mutex;
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+ WaitQueue _waitQueue;
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+};
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+
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+
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+} // namespace Poco
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+
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+
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+#endif // Foundation_Condition_INCLUDED
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